Electromagnetic nature of dark energy

TL;DR

This paper proposes a novel electromagnetic explanation for dark energy, suggesting a third physical electromagnetic mode generated during inflation can account for the universe's accelerated expansion without new physics.

Contribution

It introduces a quantization approach allowing a third electromagnetic state, linking it to dark energy and the cosmological constant within standard inflationary cosmology.

Findings

A new electromagnetic mode can generate an effective cosmological constant.

The model is consistent with local gravity tests and reduces to standard QED in flat spacetime.

Primordial fluctuations could explain the observed dark energy value.

Abstract

Out of the four components of the electromagnetic field, Maxwell's theory only contains two physical degrees of freedom. However, in an expanding universe, consistently eliminating one of the "unphysical" states in the covariant (Gupta-Bleuler) formalism turns out to be difficult to realize. In this work we explore the possibility of quantization without subsidiary conditions. This implies that the theory would contain a third physical state. The presence of such a new (temporal) electromagnetic mode on cosmological scales is shown to generate an effective cosmological constant which can account for the accelerated expansion of the universe. This new polarization state is completely decoupled from charged matter, but can be excited gravitationally. In fact, primordial electromagnetic quantum fluctuations produced during electroweak scale inflation could naturally explain the presence of this mode and also the measured value of the cosmological constant. The theory is compatible with all the local gravity tests, it is free from classical or quantum instabilities and reduces to standard QED in the flat space-time limit. Thus we see that, not only the true nature of dark energy can be established without resorting to new physics, but also the value of the cosmological constant finds a natural explanation in the context of standard inflationary cosmology. Possible signals, discriminating this model from LCDM, are also discussed.